Why is it that women pick up on the slightest slur and never hear the good stuff? Criticisms are stored forever;
compliments evaporate instantly.

My goddaughter, visiting from college, is sprawled on my bed while we enact one of our regular rituals: I peruse my closet, offering her the clothes I no longer wear. "Take this, I don't have the legs for short skirts," I say, or "These pants make me look hippy." She regards me with quizzical amusement, suggesting that I have body dysmorphic disorder—that I'm one of those people preoccupied with minor, and often imaginary, flaws in physical features. At the very least, she insists, I need new glasses.

And we're not talking mere physical insecurity. When I meet a book editor about a potential publishing contract, I fret about my abilities, discounting a thriving career and a reputation in good standing of more than 20 years. If guests are coming for dinner, I worry that my home won't be pleasing, that my brownies won't merit the caloric expenditure, that the conversation won't be sufficiently scintillating. Somehow I manage to navigate life fairly well, to earn a living and have relationships, to walk without weaving and chew without spitting. But as I watched the movie Pretty Woman recently, it occurred to me that plenty of us have the same self-doubt that derailed the Julia Roberts character. There's a scene where she's telling the wealthy businessman played by Richard Gere that nobody ever plans to be a hooker, that she fell into this line of work because she didn't think much of herself. Gere observes that she's a special person with a lot of potential and capabilities. And she replies, "The bad stuff is easier to believe."

Why it that some people, the Donald Trumps of the world, seem to believe only the best about themselves, while others—perhaps especially women, perhaps especially young women—seize on the most self-critical thoughts they can come up with? "It turns out there's an area of your brain that's assigned the task of negative thinking," says Louann Brizendine, MD, a neuropsychiatrist at the University of California, San Francisco, and the author of The Female Brain. "It's judgmental. It says 'I'm too fat' or 'I'm too old.' It's a barometer of every social interaction you have. It goes on red alert when the feedback you're getting from other people isn't going well." This worrywart part of the brain is the anterior cingulate cortex. In women, it's actually larger and more influential, as is the brain circuitry for observing emotions in others. "The reason we think females have more emotional sensitivity," says Brizendine, "is that we've been built to be immediately responsive to the needs of a nonverbal infant. That can be both a good thing and a bad thing."

The hormonal surges in the female brain—what Brizendine describes as the rising tide of estrogen and progesterone—make a woman more sensitive to emotional nuance, such as disapproval or rejection. The way you interpret feedback from other people can depend on where you are in your cycle. "Some days the feedback will reinforce your self-confidence," says Brizendine, "and other days it will destroy you." Her decision to make this hormone cycle in the female brain the focus of her research was made in medical school, when she was working with adolescents at Yale–New Haven Hospital. "How teen girls come to believe bad stuff about themselves really captivated me," she says. "There's something about the menstrual cycle that puts your emotional self in a bad light at least a few days every month. About 90 percent of women feel some kind of increased emotionality two to four days before their period starts, where they're crying over dog food commercials. I wanted to get a message to girls who are slipping down some slippery slope and get a safety net under them."